Plants 'remember,' adapt and survive

LUBBOCK, Texas -- No one's talking about giving intelligence tests, but researchers say they've shown that plants have smarts -- the sort needed to help them survive dry times.

Years from now the findings could lead to crops that are better able to withstand drought conditions. Already, studies on two crops have shown they too have short-term memory for surviving dry times, University of Nebraska-Lincoln researcher Michael Fromm said.

He contends his team's findings are the first of their kind in life forms above yeasts.

The outcome of Fromm's initial study, with a member of the mustard family, confirmed what many nursery professionals and home gardeners have observed: Stressing plants helps them adapt and aids them in surviving transplanting.

"It's important that it's in all plants, but the next part of the story will have to move the research forward," Fromm said. "There's no question this is a critical long-term problem. Drought tolerance is extremely important but it's also extremely difficult."

He declined to name the two crops he and his team studied subsequent to work with Arabidopsis -- the mustard plant -- citing confidentiality issues with the peer-reviewed journal scheduled to publish those results later this year.

In the mustard plant research, Fromm and his team compared reactions of plants stressed by withholding water to those that got water. The ones that went without water -- the trained or stressed plants -- bounced back more quickly the next time they got dehydrated. Those that got water -- the untrained or non-stressed plants -- wilted faster and their leaves lost water at a faster rate than the trained ones.

There were changes at a molecular level when the trained plants were deprived of water again. When water was then made available, the changes reverted back to normal levels. That changed, though, after subsequent periods of drought as the plants "remembered" their molecular response to stress.

"There's a connection between the environmental stress, the drought, and the plant response with not only physiological changes but developmental changes," Fromm said. "That's a decision the plant makes that we think this process can influence."

The mustard plant forgot the previous stress "memory" after five days of watering, but the researchers said other plants' memories could be different.

"It kind of backs up what a lot of people have thought," Texas Tech horticulture professor Thayne Montague said. "Once a plant is exposed to stress, drought ... it can be a beneficial response short term. Now, long term, that hasn't really been looked at."

One Lubbock woman, president of the city's 60-member master gardener program, said she thinks a plant's roots are keys to drought survival. The shorter the root, a result of overwatering, the less the plant will tolerate drought.

"Plants don't think," Barbara Robertson said. "It almost has to have something to do with the root system. A stressed plant with deep roots is going to do better."

The Nebraska research team's results could be transferred to row crops, such as corn, cotton or wheat, but that potential is still about 20 years away, Fromm said. Ideally, the goal would be to have the memory last from growing season to growing season.

"That may or may not exist," Fromm said. "Our discovery goes just a few days."

Murray Coulter, a genetic biologist who taught at Texas Tech University for more than three decades, said Fromm's research isn't saying plants have a central nervous system and can think. But if it's just one gene that needs modifying, he said, he thinks the technology could be in crop fields in five years.

That would help producers in the world's largest contiguous cotton patch, on the South Plains.

"Having a dry season would not impact them economically," Coulter said. "The less water they use, the more profit they make."